1. Field of the Invention
The present invention relates to a power source device for supplying an electric power from a battery housed in a battery box to a motor for driving the vehicle, and to a battery cooling structure for cooling the battery by cooling air flowing through a cooling passage provided in the battery box.
2. Description of the Related Art
Japanese Patent Application Laid-open Nos. 2003-317813 and 2005-71759 disclose a battery cooling structure in which a battery box housing a battery for supplying an electric power to a motor-generator for a hybrid automobile is disposed in a front portion of a trunk room provided in the rear of a rear seat, and an intake duct and an exhaust duct for supplying and discharging cooling air for cooling the battery are connected to a left or right side face of the battery box.
When such a hybrid automobile is subjected to a side collision, it is necessary to protect the battery box from the damage, however, if a special reinforcement for protecting the battery box is provided, there is a problem that the weight of a vehicle body is increased, thus lowering vehicle performance.
Generally, left and right side frames disposed in a longitudinal direction on a side of a vehicle body are interconnected and reinforced by a laterally disposed cross member. A large load is applied from an upper end of a damper of a suspension system, particularly, to the side frame corresponding to a position corresponding to a wheel housing of a rear wheel, but if a power source device is mounted at such a portion, a space for disposition of the cross member is eliminated leading to a possibility that the rigidity of the vehicle body becomes insufficient.
Also, Japanese Patent Application Laid-open No. 8-310256 discloses a battery cooling structure in which a U-shaped cooling passage is formed within a battery frame which houses a battery for an electric automobile, and an intake duct and an exhaust duct are connected to a suction port and a discharge port formed at opposite ends of the cooling passage.
In this conventional structure, the cooling passage within the battery frame is formed into the U-shape, so that the suction port and the discharge port of the cooling passage are disposed adjacent each other at opposite ends on a shorter side of the battery frame. Therefore, there is a problem that the degree of freedom is largely limited for the layout of the intake duct and the exhaust duct connected to the suction port and the discharge port.
Further, Japanese Patent Application Laid-open No. 2001-233064 discloses a battery cooling structure in which a power source device for supplying an electric power to a motor-generator for a hybrid automobile is housed within a cover which supports a seat cushion of a rear seat, and cooling air for cooling a battery of the power source device is drawn in through an air path formed in a clearance between an upper surface of the cover and a lower surface of the seat cushion.
If the external air is directly used as cooling air for cooling a battery of a power source device for a hybrid automobile or the like, there is a possibility that the battery-cooling effect is reduced in a summer season in which the temperature of the external air is high. Therefore, it is desirable that air in a vehicle compartment conditioned to an appropriate temperature is used as cooling air.
As described above, even when there is demanded for using the air in the vehicle compartment as the cooling air for cooling the battery of the power source device, if the power source device is disposed in a trunk room in the rear of the seat, there is a problem that it is difficult to guide the air in the vehicle compartment to the power source device without degradation of the sitting property of the seat.